Manually operated pipe wrenches and tongs have been used for many years for applying torque to a threaded pipe joint as is exhibited by U.S. Pat. Nos. 443,312, 2,540,553, 3,122,952, 3,752,016, 3,880,024, 4,305,316, 5,062,326 and 5,546,833. In each of these cases a pipe wrench of some type is secured to each of the coupled pipe members in a manner whereby one of the pipe wrenches may be manipulated to rotate one of the pipe members while the adjacent pipe member is retained. The long torque arms of the pipe wrenches provide a significant mechanical advantage. A threaded member used to exert force on the torque arms in a retracting or extending manner produces and even further advantage.
Looking at the prior art as a whole it becomes obvious that the mechanical pipe coupling tools although effective in most case were simply too large, slow and cumbersome for use in coupling and uncoupling oil field tubular members. It should be noted that there are several disadvantages such as; (i) the need to remove the apparatus from the pipe and reverse the procedure when changing from a make-up to a break-out procedure (ii) the lengthy torque arms, (iii) and the tendency of the pipe wrench jaws to mar the pipe surfaces. Therefore, the process evolved into faster hydraulically driven power tong units. However, recently the older mechanical pipe tongs are being resurrected for specialty operations where it is impractical or impossible to use power tongs as a result of their great bulk and need for a power supply. In such operations there is a need for a relatively fast manual tong unit, that is both compact and portable, is capable of producing a high torque on the pipe coupling without significant marring of the pipe and need not be physically reversed on the pipe when changing between break-out and make-up operations. There is also a need to readily determine the make-up torque applied to each joint.